EHIZOPODA FROM NORTH AND SOUTH AMERICA. 203- 



Family Vampyrellida. 



Yam-pyr-rlla LATEniTiA (Fresen.), Leidy. 



Leidy (6), p. 2o3, pi. 45. figs. 10-16. 

 Vampyrella spirogyra;, Cienk, in Arch. mikr. Anat. i. (1865) p. 218, pis. 12, 13. figs. 44-65., 



At West Point, N.Y., and in a pool on the Palisades, N.J., opposite Harlem,, 

 this species occurs numerously. Individuals kept under observation fed 

 freely on filaments of Spirogyra (cells 30 /x diam. and 70-80//. in length) ; the 

 contents were abstracted by the animal apparently dissolving an oval apei'ture, 

 10-12 yt6 in length, in the cell-wall; through this, pseudopodia were thrust and 

 the cell-contents absorbed, then the transverse cell-walls were attacked, and 

 a very small hole, about 2 jx in diameter, was made in each by the extremity 

 of a pseudopodium which was then used to abstract such of the contents as 

 were within its reach, a portion usually being left. After three adjoining cells 

 had thus been more or less completely emptied, the Vampyrella moved along 

 the filament for a distance of 3 or 4 cell-lengths and repeated the process. 

 Whilst feeding, the animals did not increase noticeably in size but became 

 green ; this colour, however, soon disappeared, and the normal brick-red colour 

 was resumed. 



Frequently accompanying the Vampyrellce were a number, 4 to 8, of small, 

 amoeboid sporozoa, 6 to 8 /i in diameter ; they appeared to search the Spiro- 

 gyra filament for the large openings made by the Vampyrella, through these 

 they entered the empty cells and then searched the end walls for the small, 

 perforations that had been made, squeezed themselves through, and fed on 

 such portions of the contents of the cells as had been beyond the reach of the 

 Vampyrella. These sporozoa had a well-defined nucleus and small vacuole, 

 whilst within the cells they displayed two or three sharply pointed pseudo- 

 podia ; they became green and larger after feeding, and frequently some 

 were unable to emerge through the small perforation until the process of 

 digestion had reduced them in size. 



Order CONCHULINA. 



Family Arcellida. 



Arcella curvata, sp. nov. (PI. 15. figs. 3 & 4.) 



Arcella discoides pars, Leidy (6), p. 173, pi. 28. figs. 32-36. 



Test of medium size, light brown in colour, circular, the ventral face 

 curved so as to form a portion of a cylindrical surface subtending an angle of 

 80°-100°, the dorsal face forming a dome of moderate height ; aperture 

 large, circular, invaginated, bordered by numerous small pores ; plasma 

 greyish, granular, usually including many' food-particles ; the nuclei not 



